Digester



(No Model.)

S. SMITH. DIGESTER.

Patented Dec. 30, 1890.

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UNITED STATES PATENT OFFICE.

SIDNEY SMITH, OF CAMBRIDGE, MASSACHUSETTS.

DIGESTER.

SPECIFICATION forming part of Letters Patent No. 443,923, dated December 30, 1890.

Serial No. 306,590. (No model.)

To all whom it may concern:

Be it known that I, SIDNEY SMITH, of Cambridge, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Digesters, of which the following is a specification.

The object of this invention is to produce a digester or closed box in which vegetable ber may be cooked in suitable pulping liquors known and used for the purpose without detriment to the digester. Such a receptacle of steatitewhen combined with a firebox and tortuous ues immediately under or around the box constitutes a suitable digester for the treatment of wood or any substance used as the source of vegetable fiber in the paper-manufacture.

Steatite is used in this digester for the following reasons: First, it is not attacked by any chemicals employed to act on said fiber; secondly, it has the least expansion of any substance which could be used for the purpose, and, thirdly, it absorbs heat and imparts it to the liquor inside the digester without itself being burned or burning the solid contents within. Furthermore, the long tortuous iiues under the box of steatite eifect a most thorough utilization of the heat, and at the same time the perfect distribution of heat to all parts of the digester produces a rapid uniform cooking, which is essential for :making the best pulp.

The box is made from slabs of steatite of sufcient strength and size, or blocks of steatite can be used. lVhen slabs are used, they may be in one piece or rabbeted together to form the walls of the box or digester, as convenient. For the purpose of joining the slabs to form a box dovetailed grooves are cut in the stone a little wider than is necessary to receive the corresponding piece to be fitted in. This slight extra space in the groove is to be tightly filled with sheet-lead or by pouring in molten lead in such a way as to make a perfect joint.

The digester is so placed as to form the top of a tortuous series of long flues made of brick-work in connection with a suitable lirebox. A damper is also provided which allows the products of combustion to traverse these long` flues under the digester until they finally pass off to the chimney or check the fire or cut it off entirely from the flues. In this way the contents of the digester can be kept at that uniform and even temperature which is necessary for rapid and uniform cook 111g.

, Man-holes, blow-offs, pressure-gages, and thermometers with all proper connections are provided as for any steel or iron digester.

To strengthen the steatite digester, trusses of steel or iron of sufficient size and form are placed and adjusted on the outside, so as to withstand any strain to which they are liable to be subjected.

Of the accompanying drawings, forming a part of this specification, Figure l represents a top view of a digester embodying myinvention. Fig. 2 represents a front elevation of the same. Fig. 3 represents a section on line 0c, Fig. l. Fig. 4 represents a section on line y y, Fig. 2. Fig. 5 represents a section on line z e, Fig. l.

The same letters of reference indicate the same parts in all the gures.

In the drawings, o, represents the digester, the sides of which, as here shown, are composed of four slabs 2 2 3 3 of steatite, said sides, with suitable ends or heads l t of the same material, constituting a rectangular receptacle, preferably of oblong form. Said slabs may be secured and their joints packed in any suitable way. l have here shown the slabs 2 2 provided with grooves 5 5, which receive the edges of the slabs 3 3. Said grooves are wider than the thickness of the slabs which they receive, and each is preferably of dovetail form at its inner edge, so that packings or fillings G, of lead or other suitable material not affected by the chemicals employed in digesters of this class, placed in said grooves will by iitting said dovetail edges be retained firmly in place.

The digester is placed on a support c of masonry and secured thereto in any suitable way, as by plates or bars e extending across the top of the digester, similar plates or bars f embedded in the masonry, and rods g g connecting the bars e with the bars f, as shown in Fig. 2 Vertical bars e may also be placed on the sides of the digester and connected at their upper and lower ends by cross-rods f', all as shown in Figs. l, 2, and 3.

t' represents a furnace, which is located at IOO one end of the digester and communicates with a tortuous series of fines j, which extend back and forth under the digester, as shown in Fig. 4, and conduct the heated products of combustion along the bottom of the digester, the last iiuej entering the stack or chimney c. If it is desired to decrease the heat or entirely shut it off from the digester, the pro ducts of combustion may be passed directly to the stack through a passage m Without entering the flues j. Said passage is provided with a damper n by which it may be closed.

In case it is necessary to join two slabs of steatite end to end the abutting edges should be rabbeted, and one of the projecting rabbeted edges is cut away and preferably beveled to form a dovetail space for the reception of a lead packing.

The digester may be provided with one or more man-holes m in its top, the same being closed by covers n', held in place by bolts o engaged with yoke 29', as shown in Figs. l and 5.

The contents of the digester may be removed through a blow-olf pipe s passing through one of its ends, as shown in Fig. 3.

I claim- 1. A digester composed of slabs of steatite,A

packing 6 at the joints of said slabs, said packing forming parts of the inner surface of the digester, and suitable external binding or clamping devices holding the slabs and packing in the form of abox or receptacle, for the purpose set forth.

2. A digester composed of a series of steatite slabs, some of which have dovetail grooves receiving the edges of the others, and lead packings or splines'inserted in said grooves.

3. A digester made of steatite, combined with a support having a tortuous series of iues under the digester, and a furnace communicating with said fines, as set forth.

4. A digester made of steatite, combined with a furnace, a support having a tortuous series of lues leading from the furnace to the chimney under said digester, and a direct passage m from the furnace to the chimney. avoiding the digester, said passage having a damper n, as set forth.

InA testimonyv whereof I have signed my name to this specification, in the presence of two subscribing witnesses, this 3d day of April, A. D. i889.

SIDNEY SMITH. lVitnesses:

C. F. BROWN, A. D. HARRISON. 

